Repair battery corrosion on the CPU board

Steps

• Remove the parts in the damaged area: corrosion can ruin the 40-pin processor socket at 3D, the RAM socket at 5D, the EPROM sockets at 5B and 5C and the battery holder.
• Scrub the area with a half-and-half mix of white vinegar and water to neutralise it.
• Rinse with clean water and let the board dry completely.
• Sand any grey, corroded copper back to bright metal.
• Fit new sockets and parts, then check every trace in the area for continuity; breaks are often invisible.
• Fit a remote battery holder so it cannot happen again.

Leaking alkaline batteries are caustic; wear gloves and keep the residue off skin and eyes.

Systems

• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b

Related tips

• Repairing battery corrosion on the CPU board
• Battery orientation on Data East and Sega CPU boards
• Check that battery power reaches the RAM at 5D
• Fit a remote battery holder
• Change the CPU backup batteries yearly, with the game on
• "Memory Error, Open Door" or "open the coin door" at power-on
• New batteries but still a memory error: check D25
• Judging battery corrosion damage

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)